Mining of sulphur



Jan. 18, 1927.

R. H. STEWART MINING 0F SULPHUR Filed March 15, 1924 INVENTOR Jarr- WB-A M W ATTOR NEYS x 54 STATE PATENT, oI- F ce-I Ronnnr Irommn simmer, or'vancouvnn, nmrsn cotul niu, cananaass'mnoa r 'rnxas eumr sunrnpn courm, or raw roan, at. Y., a conronarron or minus. p

Minu e or "summon. Application filed much 1t, 1934 s mi No. 888,448.

This invention relates to'improvements in oint of water at atmospheric pressure, the the'mining of sulphur, and includes an imea'tmg water is h ghly superheatedand is proved method for ,the minin of sulphur pumped into the mine under a high pressure. y'underground fusion, as we as an imhe temperature to'whlch the water can be 0 proved system or apparatus therefor. superheated is however limited by' the dan- In the mining. of sulphur by underground ger of overheating the sulphur 1n Whlch 'lh ;fusion, in accordance with the so-called case itbemmes viscous. Accordingly, the r Frasch process, a hole orwell is drilled water is heated to a tetmlperature wh ch throu hthe overlying stratato the bottom of arcade overheating of the hur but which the sulphur formation, which hole is? usually is sufliciently above the me ting pointof cased with an 'eiiht-inch or ten-inch pipe, sulgihur to brin about effective meltingfi the and -then, throng a system of concentric theme as the hi ly heatedwater comes pipes appro riatel arranged withinthis in contact with e underground'sulph-ur. casing, super eated water is um down The "water mag thus be heated under presto the foot of the hole or w w are it is sure to'about F. and pumped into-the discharged into the sulphur-formation "and, sulphur deposit this "water replacing the melts t e sulphur. The melted and liquid sulphur remove by the well to ether with sulphur enters one'of the concentric pi cs, water already ,contamed m t e deposit, usually' through a strainer, and is raise to which may be withdrawn by means of bleeds ,20 th surfac of the ground, generally by wells, situated atsuitable' points in-the demeans of-an air lift: The well continues to poslt. 'The bleed wells 'are usually located operate and produce sulphur until thefsulas to withdraw the pold brine or salt p ur-bearing formation is local] exhausted, water fnom the lower part of the sulphur or until the i ing equi finentis broken by formation. n a 2 subsidence oft e ground due to the extrae- 'The sulphur dome may underlie a-consicb' tion of the sulphur content. erable surface area of grounds The dome The 1 sulphur formation is usually found may, for example, be as much as a mile'in in the form of so-called domes, at depths diameter; and the underground lake formvarying from around 500 to 1500 feet below mg a part of the deposit or adjacent thereto 30 the surface of the ground. These sulphur may contain billions of gallons of underdomes-are usually overlaid by a porous cap ground water orbnne; a

as found a layer of or auhydrite, an

' f rock formation of limestone-which inturn ;In the mining of sue-h a sulphur de 't,

I'is overlaid b mho, quicksand nd cla one or se'veralwells are usually drillecl fid Beneath the su phur formation is usua operated, at one part of the dep sit unt l 5 thesulphur bearing formation is exhausted layers or domes o 4 p The sulphur formatioii itself-usually con-v another part of the-de osit and the deposit the sulphur distributed in a porous is progressively wor in is way until ex 'z ck formation which also contains-a large hausted. The operation ofa sul hurmine 4e amount. of water formi what may be c'onin this we is an operation of lgrge magsidered an undergroun lake of brine or .nitude. e amount of highly hen ed water saltwater containing, for example, about which it is necessary'to pump into the do; 4809 grams per gallon of solid in solution, posit in a single day may amount to several mainly sodium chorlde and in addition'hy- -million g'allons'in commercial operations.

45 drogen sulph de and other soluble sulphides. The pumping of a large amount of super- Such water 18 corrosive and destructive to heated water into the deposit results in the the; well-pipes and other metal with which gradual accumulation of a. progressively in- 1t comes in contact. creased'amount of hot water in the deposit- In the so-called Frasc-h system of mining The specific. gravity of the original deposit to sulphur by underground fusion, hot wateremperature for exampleabout 108 F.,whi-le is the vehicle commonly used for conveying temperaturefor example about 1Q8 -F'.,whlle and transmitting heat to the sulphur. Inthe specific gravity ofthe clean hot water asmuch as sulp ur melts at a temperature Bum d into the mine is in the neighboraround 240 F., which is above the boiling cc of 0.91. Owing to this difference in locally and then'other wells are drilled at prod by a water specific gravity, the hot water rises or tends to rise to the top of the dome dis lacing the cold deposit water downward, an while there is some difiusion and mixing, in a. general way the water at the top of the dome becomes cleaner and hotter with only a small amount-of solids in solution, while the water in the lower part of the deposit contains its original content of dissolved solids until dis laced by the cleaner water from above.

he rapid filling of the dome, or the up er portion of the dome, with hot water in t is way, may be ob'ectionable; as it may result in the melting o a large quantity of sulphur which may be so situated that it will not drain through the wells which are being operated, on account of the large area of the dome, and this sulphur will become discolbeing hel for a considerable time in a molten condition, before it can be extracted.

.Furthermore, the continued supply of a large amount of highly heated water to the mine forms one of the major expenses of the operation, this water being commonly obtained from a source several ,miles distant from the mine at a temperature around, for example, 68 F", and being heated to a temperature around 324 F. before it is pum d mto the mine. Of the total heat supp ied to the water, only a small art is avai able for melting the sulphur. bus, in heating from 68 F. to 324 F., 256 B. t. u.s are supplied by the combustion of fuel to each pound of water which is umped into the de osit. Since sulphur me ts at around the only efiective heat supplied to the Water is that between the rature of the water and the melting point oi-sulphur, for example, around 85 B. t. u.s of the total of 256 B. t. u.s supplied to the water.

moved an replace The present invention provides an improved method and system of mining sulphur whereby important economy of operation' is obtained, and wherebythe mining of the dome as a whole can be 'betterregulated and controlled, and whereby a greatly increased fuel efliciencg, and decreased fuel consumption can be e ected;

The present invention is of particular advantage in the mining of sulphur from deosits which have been 0 erated for considerable time until there as accumulate a large amount of hot water in the u per portion of the dome or formation rom which the sulphur has been exhausted. If fresh hot water were continually pumped into the deposit and permitted to accumulate therein, the hot water collecting in the top of the dome would gradually displace the cold deposit water downward until eventuall with suitably locatedbleed wells, all of t e ori 'nal desosit water would be reby fresh water which in maximum temthe well where turn will be replaced by hotter fresh water until the whole deposit would become heated, and heat would be wasted by further bleeding. This ra id accumulation of hot water, and ra id d:splacement of the cold brine water ownward, would serve to heat the lower part of the deposit, including those parts remote from the point where the sulphur is bein' mined; and although the hot water from aioveis cooled as it works downward by heating the deposit, and although there would be a descending scale of tem perature as lower levels in the deposit were reached, yet the heating of the deposit would not be regulated in a manner best" ada ted for the satisfactory miningof the sulp ur.

According to the present invention, this rapid fillingof the deposit area with hot water is avoided; and the operation of the deposit is regulated and controlled in such away that the heating is most effectively ap lied where it is desired.

n the ractice of the present invention, a partof 't 1e, hot water from the top of the deposit, after a large accumulation of hot water has occurred, is withdrawn and reheated and utilized over a ain by introducing it into the sulphur wel s; and this withdrawal and reutilization of the hot water a from the mine is regulated and controlled so as to givearegulation and control of the mining operation.

The resent invention includes an improved method and system for withdrawing hot water from the mine and for reheating and reutilizing this water.- The invention also includes improved methods for heating the water-so as to enable it to be used in a regulated and advantageous way in the carrying out of further mining operations.

In the carr ing out of the present invention, I with raw hot water from the top or upper art of the dome or deposit where it accumu ates in the exhausted area and in the porous cap rock, and I maintain this water at a temperature above the boiling point of water at atmospheric pressure eeping the water is being withdrawn, and I reheat while still maintaining it under pressure an again force it down into the deposit through the active min'ng operation is going on. This hot water in the to of the deposit forms a heat reservoir w ere the heat is not utilized to melt'sulphur and where only a heat loss is involved in the usual mining operation. Insteadqf obtaining only a low heat eiliciency from the hot water pumped down into the ground by permitting it to accumulate and increase in amount in the deposit, I'withdraw a part of this water from, the part of the deposit where it is at a high temperature and referably where it is this water accumulation of hot water which would take by under pressure while it Ill) ' place if this water were not so withdrawn, and if only'cooler or cold water from the lower art of the deposit were withdrawn throng bleed wells.

' Furthermore, I reintroduce this water after the addition of suflicient heat to give the maximum heating efliciency, (i. e. the necessary heat units to raise the tem erature of the water to about 320 F.), in t e localized well zone or zones where its heat is utilized,- and I thus obtain a regulated flow, so to speak, of hot water from the well zone to e topof the de osit from which it is again withdrawn for Eirther reheating and reintroduction into the deposit at the well zone. I do not, however, in ordinary operations, withdraw an amount of hot water equal to that introduced'into the mine, but I intro-.

duce a somewhat larger amount of hot wa-' terthan the amount which I withdraw, sothat there is a progressive but gradual increase in the amount of hot water accumulating in the deposit. In conjunction with this introduction of hot water and withdrawal of hot water, I also withdraw cooler water or cold water through bleed wells from the lower levels of the deposit. This is the operation which ,the invention involves during the period when there still remains cold minewater requiring to be removed.

When eventual] the, original mine water withdrawn, and replaced by hot water, through bleed wells would involve-an important heat loss, I may withdraw an amount of hot water from the deposit nearly equal to the amount reintroduced. By regulating .the amount of hot water withdrawn, in rela tion to the amount of hot water introduced, I am enabled to operate the deposit as a whole, or localize parts of'the deposit, in a particularly advantageous way; and I am enabled to change the operation so that, at the. beginnin 0 ma be introduced without any withdrawal of ot water, until a substantlalaccumulm tion, has occurred; and I may then withdraw a regulated amount of hot water, less than the amount reintroduced, so as to obtain a gradual and regulated increase in'the amount of hot water in the deposit; until finally I may withdraw hot water at a rate approxi-' mating that at which the hot water is reintroduced. 1

In the carrying out of the recess of the invention, the hot undergroun water, which is at a high temperature and pressure, e. g. at a temperature between 200 F. and 300 F. or more and at a ressure of ater than atmosphere is with awn and ept under pressure while it is being withdrawn, by means of a pum an injector or other, suitable means, an under pressure and with its temperature maintainedis used as a. vehicle or conveyor jected so thatfurther loss of waterthe operation, hot water this water so withdrawn.

for additional heat units and is then again introduced into the deposit, One advantageous method of ma ntaining this water under pressure, and of reventin it from being cooled to 212 F. y reduction of its pressure to atmospheric, is to introduce a centrifugal pump into the line through which the water is withdrawn, and at a sufficient level to receive the water while still under a sufiicient pressure to prevent its partial va orization. t When t e hot mine water is thus .withdrawn, it is reheated, or reheated and subto purification, for example, by the use of lime, metallic iron, copper, charcoal, fullers earth or other suitable material, before'it is reintroduced. Iron or copper, for example, will serve to deposit soluble sulphides and prevent corrosion ,of the well pipe; lime Wlll serve to revent corrosion by chlorides. I Fullers eart li,.charcoal, orother suitable material will serve to remove oil,etc. The present invention vprovides various novel methods of reheatingthis mine water for reuse, as well as advantageous methods of treating the mine water for'its purification for reuse. One advantageous method of reheating the mine water is to feed into it sufiicient live steam undersuitable pressure to raise its temperature to around 320 F. so that it can be returned to the sulpln-ir-producing wells for further use in a mmin operation. This method is particularly advantageous during the later stages of the miningof the sulphur in the dome, after all or practically all of the original salt water has been removed, and after the dome is filled for the most part with relatively pure water. Ordinarily, however, the water withdrawn may not be sufficiently are to permit of its reheating and reintro action in' this way; and, in such cases, the present invention provides for the treatment of this water so as to permit it to be reused. Where the mine water contains scale forming material, it is subjected to a treatment by, filtering or settlement in mud drums either before reheatadmixture of any considerable amount of fresh water therewith.

According toanother method of the presentinventio'n, the hot water withdrawn from the mine under pressure is admixed with fresh hot water of a much higher temperature so that the admixed mine water and fresh water will have the desired temperature for reintroduction into the deposit. no

1 plant to a temperature Fresh water can thus be heated at the boiler as far above 320 F. for example, to a temperature of about 364 F., and then mixed with the water drawn from the mine in such proportions that the resulting mixture will have a temperature of around 320 F., at which temperature it can be returned to sulphur-producing wells.

This method of reheating has the advan tage that the fresh water used dilutes the im urities in the hot water from the mine, an prevents to a large extent the formation of scale which might interfere with the operations. Thus w mm the water withdrawn from the mine contains gypsum, the heatin of this mine water without dilution would tend to cause precipitation of the gypsum, or of part of the gypsum, but the dilution of the mine water with fresh water tends to neutralize or overcome this precipitation and to hold the gypsum in solutioneven at the higher temperature of the admixed fresh and mine water. hot water with the mine water has the fur-- ther advantage that it renders posible the continuation ofthe filling of the dome with fresh water at a rate regulated by the amount of fresh water so admixed and introduced.

Instead of reheatin the mine water by steam alone, or by a mixture with hitghhly heated fresh water, a combination of ese two methods may advantageously be employed so as to obtain the advantages or certain of the advantages resulting from the use of fresh mine water and also an increased flexibility of operation whereby maximum econom is made possible.

The invention a so includes improvements in the treatment of thehot water withdraw'n from the mine for the separation of oil therefrom. I The oil which may be contained in small amounts in the hot water in the mine tends to separate from the water accumulating in the 'top of the dome and to accumulate in the upper in ers at or above the top of the hot water. e water withdrawn from the top of the deposit may thus contain appreciable amounts of oil admixed therewith. This amount will ordinarily be larger at the beginnin of the withdrawal of the water, because of the accumulationof oil which has been taking lace, and the amount of oil in the water withdrawn may, after the operation has been continued for sometime, become so small as not to cause as possible,

' trouble. Where however there is an appre- -ciable amount of oil in the water, the water is treated in the process of the present invention to separate the oil therefrom so that the oil will not be again introduced to contamin'ate the sulphur. In order to remove this oil, where it is present in a preciable amounts in the mine water with awn, the

This admixture of fresh graphic drawn, the space originally occupied b apparatus is provided with a trap or with a baflled receiver through which the water flows slowly, or with a filter such as is used for condenser water in marine or large en gine practice, and the oil is thus separated from the water before its reuse in further mining operation.

Trouble from oil can also be largely re duced or overcomeby extending the pipes through which the water is withdrawn to a point somewhat below the top of the water layer and well down into the cap rock so as to provide a-place above the lower end of thepipe where the oil can collect without being withdrawn with the water. Oil accumulating in this way can .be bled through the casing if it accumulates in sufiicient quantity, as where the water has remained more or less at rest for a considerable period of time and segregation of the oil toward the top has been permitted to take place over a considerable periodbefore the withdrawal of hot water begins.

The invention will be further described in connection with the accompanying drawing which illustrates in a conventional and manner a section of a mine and of apparatus embodying the invention and a apted for the practice of the process of the invention. The showing is largely conventional, and various parts are magnified, and the horizontal dimensions of the pipe and of various parts are magnified for con. venience of illustration.

In such a mine as represented in the accompanying drawing, the en] hur deposit is usually overlaid by a cap roc formation of limestone, above which is be, quicksand and clay. Below the sulp ur deposit there are usually bodies of gypsum and salt. In the .drawin there is re resented a re '01! marked ot water zone I from which it is assumed the sulphur has been melted, and which is, assumed to be full oihot water accumulated from the mining operation. The hot water will also extend upwardly into the porous on rock. Itwill be apparent that as the phur is melted and witii t e sulphur must be filled either 1) the su idence of the earth above or by the hot water pumped into the mine. It will also be understood, as above ex lained, that the hot water which is pumperl into the mine where the active mining operation is going lighter than the cold salt water originally contained in the mine, so that the fresh hot water tends to rise and to accumulate in the upper levels of the dome.

In the drawing, one of on, IS

a series of active sulphur wells is indicated at 1, this well being made up as usual of a series of con centric p pes within a casing tube. .For convenience of illustration, the entire series of pipes is omitted and only two concentric ion ISO

to the bottom of the 2 illustrating the outer i e within hot water pumped down into the mine is supplied in this way. The water this supplied is heated from e. g. 68 F. to around 320 or 324 F. and is supplied at the latter temperature to the mining operation.

A bleed well 5 is shown as located at a distance from the active sulphur mine and as leading from a lower level of the deposit from which the colder salt water 'will be withdrawn in re lated amount. During the early stages of tlie mining operation, the

- bleed wells may discharge salt .water at a ciently into the hot roxirnately the same rate the same as or ap notion of fresh hot as the rate of intro water into the mine.

A well 6 is shown as located so as to withdraw water from the top of the dome. This well extends down into the orous cap rock and'at its upper end is en ar'ged so as to accomodate a suitable ump, shown as a centrifugal pump 8 driven by a motor 9 and having an extension 10 extending down water zone and which may terminate in a perforated end 11 through which the hot water is admitted into the pipe 10 and thenceinto the centrifugal pump 8. The well pump 8 me be of any suitable construction for keeping the water under pressure so that'no expansion or freeing of steam can take place near or at the surface of the ground. A heav duty centrifugal pump such as a multi-stage centrifugal pum be locate at a sufficient distance below the surface of the ground to receive the water before its pressure has been reduced sulfito ermit vaporization and cooling thereby. 'l he pump ma be located for example from to 100 eet below the surface of the ground, or it may be located at even a lower level if desired.

The water pumped from the; ground )asses through the pipe 13 to the heater 12. bn its way it ma bepurified in the purifier 18 or filtered in t e filter 19, or both purified and filtered, before it reaches the heater 12.

The purifier may contain lime or other chemicals for neutralizin the acid or corrosive chemicals container in the water and the filter may remove any matter thus precipita-ted as well as any matter carried mechanically in the water, or the filter may be can be used. This pump should.

of a selective character which will absorb oil or other impurities from the water.

From the heater 12 the hot water is conl veyed by the i e 16 to the pum 17 b which it is agai ii pumped to the we] 1. y In the heater 12 the mine water ma be heatedeitlier by high pressure steam i i'om the power plant introduced through the line 15, or by admixture with hotter superheated water from the power plant introduced through the line 14, or by a combination of both of these heatin means, as above described. The heats water can be used alone or it can be admixed with additional fresh hot water entering the well through the line 4. I

At the beginning of the mining operations of the dome, the-sulphur wells are advantageously located near the top of the dome near the location of the well 6 and such wells are operated until the sulphur is exhausted at that location or until subsidence of the ground causes breaking of the iping equip ment. As the ground surroun ing the first .wells becomes exhausted, additional wells are drilled at a distance from the first wells. These wells may be at a location such as illustrated by the well 1 in the drawin and the well 6 ma be an exhausted well which is used merely fb'r the purpose ofwithdrawing the hot water from the .upper part of the deposit. The upper part of the deposit forms a water tends to accumulate in a portion of the deposit from ,which the sulphur has been exhausted and in the porous cap rock where it serves no useful purpose in melting sul phur and where it causes eat heat loss and low heat efiiciency. In t e process of the present invention, the relatively ure hot.

water is withdrawn from the ot zone where it is hottest and where the hot water is ket localized and the-hot water thus with rawn is kept under pressure so as to maintain its tem erature and it is then reheated' and 'reuti zed in the manner above described. The temperature of the water thus withdrawn may be as low as 200 F., or even lower-,but after the mining operaion has continued for sometime, the water will be at a much-higher temperature, as high as 260 F. or even higher. By withdrawing water at this temperature andadmixirig it with water heated to a much higher temperature e. around 365 F., the mixture can be so r ated in prop'drtion of the mine water an much hotter water to get a com" osite product of the prgper temperature or reintroduction into e. g. at around 320 to 324 F. It will be evident that the relative amounts of mine waterand of fresh hot water will vary with the temperature at which the mine water is withdrawn as well as with the temperature e mine heat reservoir where the hottest of the water supplied to the wells is 324 however a smaller amount one and one-half pounds of water P the wells, there IS attained two a. sea

wit hdrawn, the increased 5 about. 29.7%.

water which is with in the form of superheated fresh water, a

5 sary to heat up a corresponding amount of fresh water to the same temperature is saved. Instead of suppl ing 256 B. t. u.s per pound of water heate from 68 F. to 324 F., only 64 B. t. u.s are uired to heat a und of mine water om 260 F. to 324 F. The large economies which such reutilization of the hot ine water makes possible will be appreciated if we take an example where the fresh water is supplied 15 to the power plant at a temperature of 68 F. and where thea'verage temperature The heat required to heat one pound of is 256 B. t. us. If of water is heated to a much higher temperature, e. g. 364 F., the amount of heat is only 296B. t. u.s or

water from 68 to 324 F.

40 B. t. u.s more than for hea the same amount of water to 324 F. But ,m1x1ng eated to mine water which R, and allowing the plant and the 364 F. with one pound of is at a temperature. of 260 a loss of 4 degrees between oint of mixin and final temperature at and one-half ounds of well water at 320.F. Accordmgly, instead of heatingtwo and one-half pounds of water from 68 F. to 324 F., it necessary to heat one and one-half from 68.np to 364 F., and to admix the latter amount with one pound of mine water at 260 F., to obtain a similar amount of water at the desired temperature of 320 F. Calculating this economy in terms i of increased production .of sulphur per pound of fuel oil used in the power plant, the economy or increased production amounts to around 44 percent where the mine water is withdrawn at a tem erature of 260 F.- With mine water with rawn at 250 F., the economy is 35.8 percent 1ncreased production per pound of fuel oil. At 240 F. temperature of the mine water production is Even with the temperature of the mine water at 200 F., an increased production of sulphur of about 15.2- percent 1s obtained. economy is obtained by using the heat already contained in the mine water, and by making this hot water which is alread preheated serve as a carrier for the additional heat units without raising the final temperature above the point at which the sulphur becomes viscous.

Instead of supplying all of the heat to the rawn from the mine part of theheat may be supplied in the form of high pressure steam from the power plant. By regulating the amount of fresh permitted to accumulate and to displace the mine water downwardly at a relatively rapid rate.

Eventually, as the mine is worked to progressively lower levels, and as the mine water tends to be more or less completely removed and replaced by fresh water so that the mine becomes full or approximately full of heated water, an increased amount of the heat can be supplied in the form of steam and an increased amount of the hot water can be withdrawn and urified and returned for the continuation of the mining operation.

It will be evident that suitable thermometers and regulating valves as well'as thermostatic controlling devices can be provided for regulatin the mixing of the water from the plantwith the hot water from the mine so as to obtain a mixture for delivery to the well at the proper temperature.

The present invention enables a simplification to be obtained in the power plant which supplies hot water ',or superheated steam for theminingoperation. In such power plants, as now operated high pressure steam is generated in boilers and is admixed with water in mixers o crating on the jet condenser principle an the water is thus heated to the proper temperature for the mining operation. The feed water for the boilers or for the heaters or both may be preheated b the exhaust power plant. e same power plant can be used in carryin out the process of the present. invention, at with the utilization of a. decreased amount of steam. There should be a suflicient amount of steam for reheatingthe mine water, or steam at a bi her temperature and pressure to heat e fresh water to the nry higher temperature for admixture with the hotmine water.

. As considerable power will be used at all times for pum ing, co ressing air, lighting, heating an general istribution of electrlcal ways v heat available from the source of the various e ines' which can be used to advantage in pre eatfn the fresh water from the reservoir to say F. so that a certain amount of fresh water is always available in excess of the boiler feed water without loss of efliciency, until such time as the steam from the war around the mine,- there will al- III discharged from condensers. At such time, the use of steam in the power plant ma be cut down to a minimum by the use of ighlyelficient steam or other engines, and the heat from the exhaust may be wasted, except to the extent that it may be used for the preheatin of such feed water as is still supplied to t e power plant and mining operation. At such time as the' mine becomes practically filled with hot and clean water, a minimum of fresh hot water can be supplied for the mining operat' on and the greater part of the mining operation can be carried out by recirculation ofthe mine water, with purification and reheatin there. of b the use of steam as above descrl ed.

T e improved process of the present invention presents the advantage amon others, that the applIcation of highl heated water to the dome is localized. The hot water introduced at the mine where the active mining operation is going on tends to rise and flow towards the'top of the dome. By withdrawing the hot water from near the top of the dome, the tendency is for the hottest water introduced at the mine to flow in the d'rection of the wells through which the hot. water is withdrawn. The hottest water thus tends to stay in the upper layer of water in the dome and to be replenished by the fresh hot water flowing from the actwo wells. ,In this way, the hottest water is kept away from the sulphur bed remote from the active wells and-remote from the top of the dome and only'the cooler water at the lower levels comes 1n contact with such remote portions of the bed. This withdrawal of hot water from the top of the dome kee s down the accumulation of hot water in t 'e dome and reduces the totalvolume of new hot water introduced and accumulated "n the deposit and so tends to prevent the overheating of the deposit and discoloration of sulphur before its extraction by delaying the advance downward of the heated zone. This heated zone, as'above describedLcan be re ({uregulatm the amount of fresh hot water a ixed wit 7 the hot-water withdrawn from the mine and reheated and reintroduced therein. The loss ofsulphuraround the bottomof the edges of the deposit through premature melting before it minimized. a

It will thus be seen that the present invention involves an important economy of operations both in the amount of heat required for conducting the mining operation and in the heat which would otherwise be lost or which might even be objectionable can be extracted is also reduced "or and injurious if ermittedto accumulate increase inrthe eposit. It will further "be seen that the hot water is withdrawn at a considerable distance from the well where it is introduced but nevertheless at the point temperature isto be ound in a deposit. It will also be noted, that the bleed wells are to Y where the water of ap roximately maximumlocated at a still lower level or at a further removed point of the deposit where the water withdrawn therethrough will be the cold salt water or the cooler water from the lower levels of the deposit. f a 7 In the mining of sulphur by drilling suc-' ccssivewells to the underlying sulphur-strata of the dome, the mining can advantageously be carried out by begining near the center or top of the dome an'diworking outwardly from the centerand progressively exhaust ing the sulphur from areas more and more remote from the center. and from the top of thedome. When the wells reach a'point which is distant from the'center, and particularly a, point which 'is at a lower level, the hot water will then tend to accumulate at the still higher levels near the top' of the dome from which the sulfhur' has already been'exhausted. This is a vantageous in the process of the present invention; and the progressive mimng of the dome can be car: ried out in the manner above described and; with reutilization of, the accumulated hot water in the mine in such a we. to obtain important heat economies, as wel as to obtain advanta es in the operation of the mine itself and the avoidance of objectionable over- 'eatin at points remote from the exhausted emf active mining zones.

- It will further be seen that in the process of the present invention, the difliculties aris- I on ing from the use of the mine water are overcome and its corrosive and scale forming properties are neutralized by suitable treatment, and objectionable amountsof oil 'carried thereby are removedso as to avoid con-- tamination of the sol hur: therewith; and. fresh water is introd therewith to insure the dual. heating of the deposit down to the evel at --which sulphur is bein extracted so that ultimately that the invention provides forone ormore wellsextending ,to the top of the deposit where the reservoir of hot water has accu-- mulated together withmeans 'for pumping this hot water from the deposit and maintaining it under pressureand for reheating need in admixture 115 extractionqo sul hur from the bottom or I it and reintroducing it into the active well;

\drawn, either by high pressure steam from the power plant, or by highly superheated water, and for regulating the temperature of the reheated water and the mixing of the fresh water therewith for delivery to the wells at the proper temperature. It will further be seen that the system includes one or more wells at a point remote from the top of the dome in combination with 'a; well for withdrawing hot water from the top of the dome soas to obtain a general direction of flow of hot water in the de osit from'the active wells to the top of the ome from which the hot water is withdrawn;

while' the cold water is withdrawn from the ilep'rlisit by bleed wells extending to a lower eve The system or a paratus of the present invention also enab es aneconomy in power plant'operation to be obtained since byopcrating the power plant at. a higher steam pressure the amount of water which it is necessary to heat can be, greatly reduced. The reduction in cost of joperatlon of the power plant, and the glieat "reduction in amount of fuel required for heating water, involves large savin in operation while at the same time enab ing the mining of the sulphur in the dome to berbetter regulated, an

controlled.

I claim 1. The im rovement in the mining of sulphur by un erground fusion from partially exhausted sulp ur deposits, which com ris es withdrawing from the upper part 0 the deposit hot water, at a'temperatiire slightly be ow or higher than the melting point of sulphur, which water has preferentially accumulated in the upper art of the deposit, reheating the water withdrawn, reintroducing the reheated water into the deposit, admixing additional fresh superheated fluid therewith before introduction, and withdrawing cold water, at a temperature well below t e melting point of sulphur, from the mine.

2. The im rovement in the mining of sul phur by un erground fusion from partially exhausted sulp ur deposits which comprises withdrawing part of the hottest water from the exhausted upper part of the deposit, reheating troducmg the reheated water at a localized well zone remote from the point of with- V drawal.

. 3. The'improvement in the mining of sulthe water so withdrawn, and rein-.

prises conducting super phur by underground fusion from artialy exhausted sulphur deposits, whic comthe formation containing the sulphur and thereby melting the sulphur, continuing such introduction of superheated water and simultaneously withdrawing relatively cold water from a lower level of the deposit until a preferential accumulation of hot water occurs in the upper part of the deposit, and thereafter regulating the further accumulation of such hot water in the deposit by withdrawing a part of the accumulated hot water, at a temperature slightly below or higher than the melting point of sulphur, reheating the hot water withdrawn and admixing therewith a regulated amount of fresh superheated fluid, reintroducing the resultin admixture into the deposit, and continuing to withdraw a regulated amount of cold water, at a temperature well below the melting point of sulphur, from a lower level of the deposit.

4. The im rovement in'the of sulphur by un er round fusion from partially exhausted sulp ur deposits which comprises withdrawing a art of the hot water from near the to o the dc osit, reheating the water with rawn and adi'nixing therewith a regulated amount of fresh superheated water, reintroducing the resultin superheated water into the deposit at a we] zone remote from the point of withdrawal of the hot water, and regulating the further accumulation of hot water in the deposit by regulating the amount of fresh su rheated water admixed with the reheat water the deposit and by a regulated withdrawal of cold water from a lower. level of the deposit.

5. The rovement in the mining of sulphur by un er round fusion from partially exhaustedsulp ur deposits, which comprises withdrawing superheated water from 'the upper part of such deposit while such wateris superheated above 212 F., maintaining such superheated water under pressure to prevent va rization and cooling thereof, reheating sai water and reintroducing the eated water into ill] same into the deposit at a well zone remote from the point of withdrawal, and re latmg the accumulation of hot-water int e defliosit by introducing additional superheated uid into the deposit and separatel withdrawing a regulated amount of col water,

deposit by means of a pump located a sulficient distance below the surface of the ground to maintain the water withdrawn under pressure and. prevent vaporization thereof, pumpingthewatersowithdrawn ot water in the exhausted upper: ortion of the deposit which 'comprises wit drawing sul hur from the deposit, independently wit draw hot water at a temperature shghtly below or higher their the melting point of sulphur from such accumulation,

reheating the sameby admixture therewith su of fluid superheated toa much higher temperature, and reintroducing the reheated between 200 and 260 water into the deposit.

8. The im rovernent in the mining of su1-' phur by an erground fusion from a sul hur deposit containing an accumulation 0' hot water in the exhausted upper portion of the deposit which comprises wit drawing hot water at a temperature slightly below or higher than the melting point of sulphurfrom 'said accumulation, maintaining the withdrawn water under pressure to preventvaporization, reheating the withdrawn water by admixture with fresh lfluid superheated to a much higher temperature, reintroducing the reheated water into the deposit at a mine zone remote from thechat of withdrawal, and independently wi drawing cold water at a temperature well below the melting point of sulphur from a lower level of the deposlt. r

9. The improvement in the mining of sulphur by under ground fusion from partially exhausted sulphur deposits which comprises withdrawing sulphur from the dBPOSllJ, independently hot water irom the upper part of the dep osit at a tem erature reheating e water a so withdrawn by admixture with fresh fluid superheated to a much higher temperature to give a resulting mixture of a temperature around 320 to 324 F., andirei'ntroducing the reheated water and admi'xedfresh flui to the deposit.

10. The improvement in the mining of sulphur by underground fusion from partially exhausted sulp ur deposits which comprises withdrawing hot water at a; temperature I slightly below or higher than the .melting point of sulphur from the upper'p'art of the de osit rehea the water withdrawn re- P tmg s ells extending to the sulphur-containing,

introducing the reheated water into the deposit at a well zone remote from the-point of withdrawal, introducing additional superheated water' into the deposit at the well zone, independently withdrawing cold water at a temperature well below the melting int of sulphur from a lower level of the eposit and subjecting the hot water so withdrawn and reheated to purification for the of the of sulphur separation. ofoil'therefrom before its reintroduction into the deposit.

11, The improvement in. he mining of sulph ur by undrgrolind fusion which comprises withdravvinghot water at a temperature sligh-tl below or higher than the melting point o ,sulphur from the upper part of the deposit, reheating the water withdrawn in part by steam under pressure and in part by admixture with free superheated water at a higher temperature and reintroducing the reheated water into thedeposit at a mine point-of sulphur from a lower level of the deposit, and re lating the accumulation of hot water in t e deposit by regulating the zonc remote from the point of withdrawal.

amount of fresh superheated fluid admixed with the withdrawn water and the amount of cold water withdrawn to obtain a heated zone gradually and progressively extending downward in the deposit. n

13. In the of sulphur by underground fusion from partiallyexhausted sulphur deposits, one or more wells, arranged to permit withdrawal of hot water at a temperature slightly below.or higher than the melting oint of sulphur from near the to eposit, one or, more wells arran for, conductin superheated water into the sulphur contaming formation at a distance from the 'wells first mentioned,-means for P ly be ow or from'the top .of the deposit to the surface of the ground said first mentioned wells and for mhint such hot water at a temperature higher than the melting o nt.

water under pressure, one or more re eatersfor reheat reheaters being -supplied with a beat ng medium from a power plant located at a terms therefrom, and means. for remtroducing the reheated water into the sulphurwell or wells as the heating medium therefor, a f

1a. In the mining of sulphur one or more deposit for introducing superheated water into the deposit and for removing molten sul 'hur therefrom, one or more wells exte deposit the waterso withdrawn, said point of sulphur from the upper part of the eposit and maintaining it under pressure, means for urifying the water so withdrawn -from the epos1t,'means for admixin with 5 the water so withdrawn fresh super eated fluid, and means for introducing the resulting water into said first mentioned wells.

15. In the mining of sulphur one or more wells extending to the sulphur-containing 10\ deposit for introduc' superheated water "into the deposit and or removing molten sulphur therefrom, one or more wells extending to the upper glart otthe deposit from which the s ph'ur as been exhausted, 1B pumps in .said last mentioned wells for pumping the hot water at a temperature slightly below or higher than the melting mt of sulphur from the upper part of the eposit and mamtaming it under pressure, 20 means for reheating the water by admixture therewith of fresh superheated fluid.

. wells,

' sulphur by underground fusion from from the ower plant, means for returning the resulting water to said first mentioned .and means for withdrawing cold water at a temperature well, below the melting point of sulphur from a lower level of the e ,osit.

' 16. e improvement in the mining of artially exhausted sulphur deposits, w ch comprises withdrawing hot water from the upper part of the deposit, at a temperature shghtly. below or higherthan the melting point of sulphur, which water has preferentially accumulated in the upper part of the deposit, reheating the water withdrawn, admixin additional fresh superheated fluid therewit and reintroducing the reheated,

water into the de osit.

, In testimony w ereof I ailix my signature.

"ROBERT HOLDEN STEWART.

saint of sulphur from the upper part of the eposit and maintaining it under pressure, means for urifying the water so withdrawn from the eposlt, means for admixin with 5 the water so withdrawn fresh su er eated fluid, and means for introducing e resulting water into said first mentioned wells.

15. In the mining of sulphur one or more ture therewith of fresh superheated fluid.

from the power plant, means for returning the resulting water to said first mentioned .wells, .and means for withdrawing cold water at a temperature well below the melting point of sulphur from a lower level of the e osit. 16. he improvement in the mining of sul hur by underground fusion from artial y exhausted sulphur deposits, w ich comprises withdrawing hot water from the upper part of the deposit, at a temperature shghtly. below or higher'than the melting point of sulphur, which water has preferentially accumulated in the upper part of the deposit, reheating the water withdrawn, admixm additional fresh superheated fluid therewith, water into the de osit.

, In testimony w ereof I afl'rx my signature.

"ROBERT HOLDEN STEWART.

0 Certificate .bfQitrection- Patent No. 1,615,050, granted January-18, 1927, to a h ROBERT HOLDEN STEWART. j t

i It is hereby certified that error appeers in the printedspecification of the abovementionedlpatent req uiring correction as follows: Page forewample about 1.08, cmd.v the; and that the said Letters insert instead water 1, strike out line 104 and Patent should be rea with this correction therein "that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 22d day or February, A. 11,1927.

M. J. MOORE,

and reintroducing the reheated,

Certificate of Correction.

Patent No. 1,615,050, granted January 18, 1927, to

ROBERT HOLDEN STEWART.

It is hereby certified that error appears in the printed specification of the abovementioned patent requiring correction as follows: Page 1, strike out line 104 and insert instead water 3 for example about 1.08, mad the; and that the said Letters Patent should be read' with this correction therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 22d day of February, A. D. 1927.

[m] M. J. MOORE,

Acting 0mm of Patents. 

